FIGS. 1A and 1B are views for explaining the prior art of the present invention and show X and Y piping assemblies on a wafer stage and cross sections of the X piping assembly, respectively.
As shown in FIGS. 1A and 1B, a pressure air system comprises pressure air pipes 120a to 120e, which supply pressure air. A vacuum system comprises vacuum pipes 120f and 120g, which supply chuck vacuum air for a wafer 109 and chuck vacuum air for a wafer chuck 108. A coolant system comprises coolant pipes 120h and 120i, which supply/recover a coolant. An electrical system comprises electrical cables 120j and 120k, which supply signals and driving currents among an illuminance sensor 112 on a fine adjustment stage 107, a photosensor within a stage reference mark 113, and driving units. A Y piping assembly 121 has almost the same arrangement as that of an X piping assembly and aims at movably connecting pipes in the Y direction. A pipe coupling wire 122 binds the piping assemblies of the respective systems to connect the pipes 120a to 120g of the pressure air and vacuum systems, the coolant pipes 120h and 120i of the coolant system, and the electrical cables 120j and 120k of the electrical system in almost a belt-like manner. A piping assembly of this type and an arrangement based on the same concept are disclosed in Japanese Patent Laid-Open No. 11-030294.
However, in the above-mentioned prior art example, the pipes of the systems are separately connected to a stage movable unit. When the stage movable unit moves, the pipes of the systems may rub against each other, may warp at an indefinite position, or may warp at the pipe coupling portion. Disturbance from the connecting portion of each piping system may decrease the control accuracy of a stage.
When a stage apparatus is used in a low-humidity environment, such as a nitrogen-purged atmosphere or a vacuum, movement of the piping system connecting portions tends to generate static electricity to charge the surfaces of the respective piping members. An electrostatic spark may occur at an indefinite position between the pipes or between components on the stage apparatus to damage the pipes, the electrical cables, and the components of the stage.
The present invention has been made in consideration of the conventional drawbacks, and to provide an exposure apparatus capable of minimizing disturbance by a piping system connecting portion, dust, and electrostatic buildup on the surfaces of piping members.